Arrow entrance wounds with blackened margins simulating bullet wipe.

Crossbows are ancient distance weapons, which in modern times have been largely replaced by guns. Nowadays, they are used for target shooting and in some countries also for hunting. Bolts/arrows fired from a crossbow have a rather low initial velocity but a high penetration capacity comparable to bullets shot from firearms. A considerable number of homicidal, suicidal, and accidental crossbow injuries have been reported up to the present day both under clinical and medicolegal aspects. A recent suicide case gave rise to a systematic study of entrance wounds from field-tipped arrows with shafts made of carbon. Composite models (ballistic gelatin covered with pig skin) served as targets. As found in the suicide case presented, the roundish entrance wounds were characterized by a slit-like severance of the skin surrounded by a pronounced blackish ring resembling the bullet wipe in gunshots. The material deposited circularly on the margins was subjected to the sodium rhodizonate test, SEM/EDX analysis, histological examination, and Raman spectroscopy. As expected, the elements typical of gunshot residues could not be detected. The element pattern of the black deposits was consistent with that of the arrows' tips and carbon shafts. Histological examination revealed that the carbonaceous material was deposited on the abraded wound margins suggesting a mechanism of friction causing the transfer of material. In conclusion, the presence of a black-margined roundish skin wound does not necessarily mean a bullet wipe. The casuistic part of the paper deals with a suicidal shot to the chest in a 48-year-old man, inflicted with a field-tipped carbon arrow which perforated both the heart and the thoracic aorta. In addition, a review of the literature on fatal crossbow injuries is presented.

Bullet wipe on the uppermost textile layer of gunshot entrance sites: may it be absent due to pre-existing blood staining?

Most gunshot entrance sites on human victims are localized in clothed body regions. Except for the use of lead-free ammunition, a positive color reaction of the sodium rhodizonate test indicates a primary target hit by the bullet. Any lead residue pattern in the area around the entrance hole allows approximate conclusions as to the firing distance in close and intermediate range shots, whereas the presence of a bullet wipe denotes an entrance site. A criminal case gave rise to an experimental study to clarify whether a blood-soaked garment being shot at as a primary target may lack a bullet wipe around the entrance hole. Distant-range shots were fired with a semi-automatic pistol (Heckler & Koch, Mod. USP Compact, cal. 9-mm Luger) using cartridges with jacketed round-nose bullets and a Sinoxid primer containing lead styphnate. In fabrics saturated with fluid blood, a wide area around the bullet entrance was densely covered with rhodizonate-positive microparticles simulating gunshot residues (GSR) from a close-range shot. In shots to fabrics oversaturated with blood, a typical bullet wipe was lacking, whereas lead-containing particles were spotted in the periphery. The results are discussed with respect to the aberrant appearance of bullet entrance sites in blood-soaked fabrics.

Electrothermic damage to the nail due to arcing in high-voltage discharge.

The burn effects in high-voltage electrocutions are manifold ranging from inconspicuous marks to deep charring. Apart from lesions caused by direct contact with a live conductor, the victim's body may suffer flash burns from arcing resulting in extensive scattered or confluent heat damage of the skin. In such cases, the nail plates of fingers and toes may undergo thermal changes which up to now have not been mentioned in the pertinent literature. Macroscopically, the nail shows a yellowish discoloration with tiny and closely arranged verruciform elevations. Histologically, the uppermost layer of the nail plate is interspersed with small vacuoles resembling micro-blisters as seen in the corneal layer of common electric marks. The surface of the nail is coated with a thin film of carbonaceous material. Based on an accidental high-voltage electrocution recently observed by the authors, attention is also drawn to the possible occurrence of contact burns from metal objects heated by the current as this finding is usually described only in victims of lightning strikes and not in the context of high-voltage discharges of technical electricity.

GSR deposition along the bullet path in contact shots to composite models.

In contact shots, all the materials emerging from the muzzle (combustion gases, soot, powder grains, and metals from the primer) will be driven into the depth of the entrance wound and the following sections of the bullet track. The so-called "pocket" ("powder cavity") under the skin containing soot and gunpowder particles is regarded as a significant indicator of a contact entrance wound since one would expect that the quantity of GSR deposited along the bullet's path rapidly declines towards the exit hole. Nevertheless, experience has shown that soot, powder particles, and carboxyhemoglobin may be found not only in the initial part of the wound channel, but also far away from the entrance and even at the exit. In order to investigate the propagation of GSRs under standardized conditions, contact test shots were fired against composite models of pig skin and 25-cm-long gelatin blocks using 9-mm Luger pistol cartridges with two different primers (Sinoxid® and Sintox®). Subsequently, 1-cm-thick layers of the gelatin blocks were examined as to their primer element contents (lead, barium, and antimony as discharge residues of Sinoxid® as well as zinc and titanium from Sintox®) by means of X-ray fluorescence spectroscopy. As expected, the highest element concentrations were found in the initial parts of the bullet tracks, but also the distal sections contained detectable amounts of the respective primer elements. The same was true for amorphous soot and unburned/partly burned powder particles, which could be demonstrated even at the exit site. With the help of a high-speed motion camera it was shown that for a short time the temporary cavitation extends from the entrance to the exit thus facilitating the unlimited spread of discharge residues along the whole bullet path.

Water solubility in aluminous orthopyroxene and the origin of Earth's asthenosphere.

Plate tectonics is based on the concept of rigid lithosphere plates sliding on a mechanically weak asthenosphere. Many models assume that the weakness of the asthenosphere is related to the presence of small amounts of hydrous melts. However, the mechanism that may cause melting in the asthenosphere is not well understood. We show that the asthenosphere coincides with a zone where the water solubility in mantle minerals has a pronounced minimum. The minimum is due to a sharp decrease of water solubility in aluminous orthopyroxene with depth, whereas the water solubility in olivine continuously increases with pressure. Melting in the asthenosphere may therefore be related not to volatile enrichment but to a minimum in water solubility, which causes excess water to form a hydrous silicate melt.